Abstract:

ABSTRACT: Many researchers have focused widely on suppressing the steady state sinusoidal tracking error and the total harmonic distortion in grid-connected inverter systems. In this thesis, a sliding mode control strategy with integral and mutli-resonant controllers is used to control a single phase voltage source grid connected inverter. This method leads to a sliding surface where all the states of the system remain on and sliding until reaching the equilibrium point which is the origin in the steady state. Integral term for grid current error is added to suppress the magnitude of the error in grid current but the results show that this term has no effect on the harmonic distortion of the system especially when an external disturbance is applied to the system from the grid voltage. So, another term called multi-resonant is added. This multi-resonant term is able to suppress the magnitude of the disturbance and the total harmonic distortion in the system.
Simulation results for single-phase grid-connected inverter is shown using Simulink (matlab 2015) to prove the effectiveness of the proposed control strategy. These results are compared with the results in [11] where the tracking precision of the grid current is improved from 0.91% to 0.17% and the THD of the grid current from 0.76% to 0.05%.
Keyword: Voltage source inverter (VSI), LCL filter, Sliding mode control (SMC), Integral controller, Multi-resonant controller, Grid current tracking error, Total Harmonic Distortion (THD)